Tailoring of Si doping layers in GaAs during molecular beam epitaxy

For Si delta-like doping of GaAs lateral ordering processes and segregation in growth direction have been investigated in real time by monitoring longe-range and short-range ordering effects using reflection high-energy electron diffraction (RHEED) and reflectance anisotropy spectroscopy (RAS). When Si is supplied in pulses to GaAs(001) distinct ordering processes occur which are promoted by misorientation steps on the vicinal surface. The incorporation of Si atoms on Ga sites in a single plane can be completed to a high degree. The depth profile of the electron concentration is closely related to Si segregation during GaAs overgrowth. In the case of a doping layer of extremely high coverage it shows a minimum at the centre of the doping spike. For samples grown on vicinal GaAs(001) surfaces under conditions favourable for wire-like Si incorporation a considerable enhancement of the exciton photoluminescence (PL) intensity and decay time has been found.